1 .TH grompp 1 "Thu 16 Oct 2008"
3 grompp - makes a run input file
8 .BI "-f" " grompp.mdp "
9 .BI "-po" " mdout.mdp "
12 .BI "-rb" " conf.gro "
13 .BI "-n" " index.ndx "
14 .BI "-p" " topol.top "
15 .BI "-pp" " processed.top "
16 .BI "-o" " topol.tpr "
24 .BI "-maxwarn" " int "
28 The gromacs preprocessor
29 reads a molecular topology file, checks the validity of the
30 file, expands the topology from a molecular description to an atomic
31 description. The topology file contains information about
32 molecule types and the number of molecules, the preprocessor
33 copies each molecule as needed.
34 There is no limitation on the number of molecule types.
35 Bonds and bond-angles can be converted into constraints, separately
36 for hydrogens and heavy atoms.
37 Then a coordinate file is read and velocities can be generated
38 from a Maxwellian distribution if requested.
39 grompp also reads parameters for the mdrun
40 (eg. number of MD steps, time step, cut-off), and others such as
41 NEMD parameters, which are corrected so that the net acceleration
43 Eventually a binary file is produced that can serve as the sole input
44 file for the MD program.
47 grompp uses the atom names from the topology file. The atom names
48 in the coordinate file (option
50 ) are only read to generate
51 warnings when they do not match the atom names in the topology.
52 Note that the atom names are irrelevant for the simulation as
53 only the atom types are used for generating interaction parameters.
56 grompp calls a preprocessor to resolve includes, macros
57 etcetera. By default we use the cpp in your path. To specify a different macro-preprocessor (e.g. m4) or alternative location
58 you can put a line in your parameter file specifying the path
59 to that program. Specifying
61 will get the pre-processed
62 topology file written out.
65 If your system does not have a c-preprocessor, you can still
66 use grompp, but you do not have access to the features
67 from the cpp. Command line options to the c-preprocessor can be given
70 file. See your local manual (man cpp).
73 When using position restraints a file with restraint coordinates
76 , otherwise restraining will be done
77 with respect to the conformation from the
80 For free energy calculation the the coordinates for the B topology
83 , otherwise they will be equal to
84 those of the A topology.
87 Starting coordinates can be read from trajectory with
90 The last frame with coordinates and velocities will be read,
94 Note that these velocities will not be used when
99 file. An energy file can be supplied with
102 to have exact restarts when using pressure and/or
103 Nose-Hoover temperature coupling. For an exact restart do not forget
104 to turn off velocity generation and turn on unconstrained starting
105 when constraints are present in the system.
106 If you want to continue a crashed run, it is
114 option grompp can convert the harmonic bonds
115 in your topology to morse potentials. This makes it possible to break
116 bonds. For this option to work you need an extra file in your $GMXLIB
117 with dissociation energy. Use the -debug option to get more information
118 on the workings of this option (look for MORSE in the grompp.log file
119 using less or something like that).
122 By default all bonded interactions which have constant energy due to
123 virtual site constructions will be removed. If this constant energy is
124 not zero, this will result in a shift in the total energy. All bonded
125 interactions can be kept by turning off
128 all constraints for distances which will be constant anyway because
129 of virtual site constructions will be removed. If any constraints remain
130 which involve virtual sites, a fatal error will result.
132 To verify your run input file, please make notice of all warnings
133 on the screen, and correct where necessary. Do also look at the contents
136 file, this contains comment lines, as well as
139 has read. If in doubt you can start grompp
142 option which will give you more information
143 in a file called grompp.log (along with real debug info). Finally, you
144 can see the contents of the run input file with the
149 .BI "-f" " grompp.mdp"
151 grompp input file with MD parameters
153 .BI "-po" " mdout.mdp"
155 grompp input file with MD parameters
159 Structure file: gro g96 pdb tpr tpb tpa
163 Structure file: gro g96 pdb tpr tpb tpa
165 .BI "-rb" " conf.gro"
167 Structure file: gro g96 pdb tpr tpb tpa
169 .BI "-n" " index.ndx"
173 .BI "-p" " topol.top"
177 .BI "-pp" " processed.top"
181 .BI "-o" " topol.tpr"
183 Run input file: tpr tpb tpa
187 Full precision trajectory: trr trj cpt
195 Print help info and quit
197 .BI "-nice" " int" " 0"
203 .BI "-time" " real" " -1 "
204 Take frame at or first after this time.
206 .BI "-[no]rmvsbds" "yes "
207 Remove constant bonded interactions with virtual sites
209 .BI "-maxwarn" " int" " 0"
210 Number of allowed warnings during input processing
212 .BI "-[no]zero" "no "
213 Set parameters for bonded interactions without defaults to zero instead of generating an error
215 .BI "-[no]renum" "yes "
216 Renumber atomtypes and minimize number of atomtypes